|Year : 2016 | Volume
| Issue : 2 | Page : 61-65
Comparative assessment of the area of sealer voids in single cone obturation done with mineral trioxide aggregate, epoxy resin, and zinc-oxide eugenol based sealers
Anisha Kumar1, AR Vivekananda Pai2
1 Department of Conservative Dentistry and Endodontics, Manipal College of Dental Sciences, Manipal University, Mangalore, Karnataka, India
2 Department of Conservative Dentistry and Endodontics, Manipal College of Dental Sciences, Manipal University, Mangalore, Karnataka, India; Department of Conservative Dentistry and Endodontics, Faculty of Dentistry, Melaka Manipal Medical College (Manipal University), 75150 Melaka, Malaysia
|Date of Web Publication||18-Apr-2016|
A R Vivekananda Pai
Department of Conservative Dentistry and Endodontics, Faculty of Dentistry, Melaka Manipal Medical College (Manipal University), Jalan Batu Hampar, Bukit Baru, 75150 Melaka
Source of Support: None, Conflict of Interest: None
Introduction: Voids in the sealer mass have the potential to allow leakage through obturation. They are more critical in single cone (SC) obturation as the volume of sealer used in this obturation is larger when compared to other obturations. Aim: To compare the area of voids in mineral trioxide aggregate (MTA)-based, resin-based, and zinc oxide-eugenol-based sealers when employed with SC obturation technique. Materials and Methods: Fifteen teeth were cleaned and shaped and divided into three groups for SC obturation using MTA Fillapex, AH26, and Pulpdent sealers, respectively. The obturated teeth were sectioned at apical, middle, and coronal third, and area of voids in the sealer was assessed using a stereomicroscope and digital images and image software. The results were statistically analyzed using SPSS software and Kruskal-Wallis and Mann-Whitney tests. Results: The three tested sealers showed voids in all the sections except MTA Fillapex, which was void free in apical and middle sections. There were significant differences between these sealers regarding their section wise area of voids (P < 0.05). Similarly, there were significant differences in their overall area of voids (P < 0.05) with MTA Fillapex showing significantly least area of voids followed by AH26. Conclusions: SC obturation with MTA Fillapex sealer, which showed void free apical and middle third sections, had significantly least area of voids in the sealer followed by the one with AH26 sealer, whereas SC obturation with Pulpdent sealer had significantly most area of voids.
Keywords: AH26, mineral trioxide aggregate Fillapex, Pulpdent, root canal sealer, single cone obturation, voids
|How to cite this article:|
Kumar A, Vivekananda Pai A R. Comparative assessment of the area of sealer voids in single cone obturation done with mineral trioxide aggregate, epoxy resin, and zinc-oxide eugenol based sealers. Saudi Endod J 2016;6:61-5
|How to cite this URL:|
Kumar A, Vivekananda Pai A R. Comparative assessment of the area of sealer voids in single cone obturation done with mineral trioxide aggregate, epoxy resin, and zinc-oxide eugenol based sealers. Saudi Endod J [serial online] 2016 [cited 2020 Jul 2];6:61-5. Available from: http://www.saudiendodj.com/text.asp?2016/6/2/61/180617
| Introduction|| |
Three-dimensional obturation of root canal space is important to achieve the objectives of root canal treatment. It is carried out using a core material and a root canal sealer and employing various techniques. , Single cone (SC) obturation technique consists of using a single well-fitting Gutta-percha cone with a sealer.  At present, availability of nickel-titanium (Ni-Ti) instruments having a greater taper with corresponding sized Gutta-percha favors SC technique.  It is said that any presence of voids in the obturation allows passage of toxins to the periapex and decreases the quality of obturation. , Since Gutta-percha is a solid core obturation material, the presence of voids can be expected to occur within the sealer mass or at the interface in the obturation.  Therefore, it is very important to quantify the area of voids in the sealer mass to assess the quality of obturation and potential for any leakage through obturation.  This occurrence of voids can be very critical in an SC technique as the volume of sealer used in this technique is larger than with other techniques.  Therefore, sealers should be devoid of or display minimal voids when used with SC technique.
Based on chemical composition many root canal sealers are available such as calcium hydroxide-based, zinc oxide-eugenol-based, glass ionomer-based, and resin-based. Recently, a calcium silicate-based sealer mineral trioxide aggregate (MTA) Fillapex (Angelus, Londrina, Brazil) has been introduced for endodontic use. The chemical composition of this sealer is based on the MTA composition with additives to obtain a consistency suitable for root canal treatment.  According to the manufacturer, it has high radiopacity, low solubility in contact with tissue fluids, and expansion during setting and excellent viscosity for insertion. It does not stain the tooth and promotes deposition of hard tissue at the root apex and perforation sites.  Studies have shown that MTA Fillapex is radiopaque, biocompatible, stimulates mineralization, prevents leakage, and increases fracture resistance of the tooth. ,,
It has been reported that there are only a few studies available on the presence of voids within the sealer mass.  Further, hardly any studies have evaluated and compared the presence of voids within the sealer mass, particularly MTA based sealers, when employed with SC technique. Therefore, this study was conducted for comparative evaluation of the area of voids in MTA, resin, and zinc oxide-eugenol-based sealers when employed with SC obturation technique.
| Materials and methods|| |
Fifteen natural human single-rooted mandibular premolar teeth extracted for periodontal or orthodontic reasons were used to obtain samples in this study. Broken teeth, carious teeth, teeth with internal or external resorption, and teeth with hypoplasia were excluded from the study.
Access opening was prepared and working length was determined by inserting a no. 15 K file into the canal until the tip of the file was just visible at the apical foramen. Root canal cleaning and shaping were done using ProTaper (Dentsply Maillefer, Ballaigues, Switzerland) Ni-Ti rotary files using crown down technique up to size F3. Sodium hypochlorite (5.25%) was used as an irrigant throughout the preparation followed by 17% ethylenediaminetetraacetic acid solution to remove the smear layer and saline as the final irrigant. The prepared teeth were randomly divided into three groups, with five teeth in each group, for SC obturation using calcium silicate-based MTA Fillapex (Angelus, Londrina, Brazil), epoxy resin-based AH26 (Dentsply, USA), and zinc oxide-eugenol-based Pulpdent (Pulpdent Corporation, MA, USA) sealers, respectively.
The groups were obturated employing an SC technique following the selection of a corresponding F3 sized ProTaper (Dentsply, Switzerland) Gutta-percha cone with tug back and using their respective root canal sealers. The sealers were mixed according to the manufacturer's instructions and applied to the canal uniformly with Lentulo Spiral Filler (Dentsply Maillefer, Ballaigues, Switzerland). The selected Gutta-percha cone was coated with a sealer, inserted into the canal, and the excess portion was cut off until the cervical line. All the obturated were stored in 100% relative humidity at 37° for 7 days to ensure complete setting of the sealers. Later, the obturated teeth were decoronated at the cementoenamel junction, and the roots were marked with shallow cuts on the buccal and lingual aspects at an approximate level of 1 mm, 4 mm, 8 mm, and 12 mm from their apices using a diamond disc. The roots were sectioned through the marked cuts using a chisel to obtain the apical, middle, and coronal third sections, each with an approximate thickness of 3 ± 0.5 mm, and to obtain a total of 15 sectioned samples in each group.
Each sectioned sample was observed using a stereomicroscope (Zeiss, Thornwood, NY, USA) with a magnification × 40 and digital images were taken. The images were analyzed using the ImageJ software (National Institutes of Health, Bethesda, MD, USA) to calculate the area of voids. The results were statistically analyzed using SPSS software (version 15, SPSS Inc, Chicago, IL, USA) and Kruskal-Wallis and Mann-Whitney tests.
| Results|| |
The section wise mean area of voids in the sealer of the study groups with significant differences among them is shown in [Table 1]. The sealers showed voids in all the sections except MTA Fillapex sealer which showed no voids in the apical and middle sections but only in the coronal section. AH26 and Pulpdent sealers showed the greater area of voids in the coronal and middle sections, respectively, than in the remaining sections. The differences in the mean area of voids between MTA Fillapex and Pulpdent sealers in all the sections and between MTA Fillapex and AH26 sealers in the middle section were significant (P < 0.05). Furthermore, the differences in the mean area of voids between AH26 and Pulpdent sealers in the apical and middle sections were significant (P < 0.05) [Table 2].
|Table 1: Section-wise mean area of voids (mm2) in the study groups with statistical differences among them |
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|Table 2: Statistical differences in the section wise mean area of voids between the study groups |
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The overall mean area of voids in the sealer of the study groups with significant differences among them is depicted in [Table 3]. Accordingly, MTA Fillapex and Pulpdent sealers showed the least and most overall mean area of voids, respectively. While AH26 showed the intermediate value. The differences in the overall mean area of voids between MTA Fillapex and AH26 sealers and between MTA Fillapex and Pulpdent sealers were significant (P < 0.05). Similarly, the difference in the overall mean area of voids between AH26 and Pulpdent sealers was also significant (P < 0.05) [Table 4].
|Table 3: Overall mean area of voids (mm2) in the study groups with a statistical difference among them |
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|Table 4: Statistical differences in the overall mean area of voids between the study groups |
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| Discussion|| |
Ni-Ti rotary instrumentation employed in this study, apart from reducing the time required for biomechanical preparation, facilitates SC obturation technique due to the availability of Gutta-percha cones with a taper corresponding to the taper of Ni-Ti files.  Although SC technique can overcome certain drawbacks associated with other obturation techniques, it has few disadvantages such as limited penetration of spreader or plugger for any further lateral compaction and poor adaptation of Gutta-percha in a canal with oval or irregular or complex anatomy. Therefore, sealer and its application in sufficient volume play an important role in providing a predictable seal in SC technique. ,
It is said that single master cone needs a greater interaction with the sealer to promote the sealing and sealer is required in larger volume. , Therefore, it can be anticipated that SC obturation may be more prone to have voids in the sealer than other obturations. Furthermore, the occurrence of any such voids in the sealer, particularly in an apical area, can be very critical and relevant to the success of SC obturation. Hence, the area of voids in the sealer following SC obturation was evaluated in the current study.
The occurrence of voids in the sealer is said to be attributed to inherent factors associated with either sealer manipulation and handling or its properties or both. Voids in the sealers are said to occur due to air entrapment during mixing or carrying and coating the sealer to the canal walls. Its occurrence also depends on the density and flow properties of the sealer. 
In this study, a zinc oxide-based sealer (Pulpdent) was employed due to its satisfactory physicochemical properties.  An epoxy resin based sealer (AH26) was used due to its superior properties and numerous advantages.  A calcium silicate-based sealer (MTA Fillapex) was studied as it is a newly introduced sealer formulation for root canal obturation and, though it is claimed to have many favorable properties, no previous studies have evaluated the occurrence of voids in this sealer. 
Many techniques have been mentioned to evaluate voids.  However, root sectioning followed by stereomicroscopic examination and digital image analysis with software was employed in this study to assess the voids. Though this methodology leads to structural loss or destruction of samples during sectioning, it has many advantages such as easy to use, provides a three-dimensional view of the surface to be examined, requires no pretreatment of the specimen unlike in scanning electron microscopic examination and is associated with image analysis software to aid in eliminating human errors during the interpretation of the parameters. ,
In this study, apical section of all the groups showed either no voids or lesser area of voids when compared to middle and coronal sections. This could be due to the close and maximal fit of the single Gutta-percha master cone apically more than coronal. A recent study also showed that SC obturation had a good density in the apical portion when compared to the coronal portion of the canal.  Similarly, another study showed that apical portions of SC obturation had 100% volume percentage while middle portion of the obturation had least volume percentage.  It has been shown that despite the close match between the greater taper SC and canal instrumented with greater taper Ni-Ti files, apical portion of the sealer was found to be thinner than the coronal portion.  It can also be expected that a greater taper SC with close fit can generate more hydraulic forces while seating it and further increase the flow of sealer apically by means of shear thinning mechanism.  This may probably cause compression or collapse of air entrapped bubbles under pressure, and/or filling of voids by the enhanced flow of the sealer and could result in a lack of or lesser voids in the apical sections. However, as the SC is pushed into the canal some of the excess sealers get displaced and backflows coronally. This could lead to a tendency for air entrapment and probably may explain the occurrence of more voids in middle or coronal sections than apical one.
In this study, SC obturation with MTA Fillapex and AH26 sealers showed significantly better results than those with Pulpdent sealer. The occurrence of voids in a sealer can be attributed to, apart from its manipulative and handling properties, the rheological properties of a sealer. Therefore, significant results seen with MTA Fillapex and AH26 sealers when compared to Pulpdent sealer could be attributed to their better flow properties which are generally related to the composition and particle size of the sealer. Further, the paste/paste formulation and resin additive in MTA Fillapex sealer and recommended low powder/liquid ratio along with the presence of resin in AH26 sealers also contribute to their better flow when compared to Pulpdent sealer which is a regular zinc oxide-eugenol-based powder/liquid formulation. ,,,,, Though results between SC obturation with MTA Fillapex sealer and those with AH26 sealer were not significantly different particularly in the critical apical section, the former one showed void free apical and middle sections. This could be due to the void filling which can be logically related to the setting mechanism of MTA Fillapex sealer.  MTA Fillapex sealer is said to exhibit a setting expansion due to the presence of MTA. It is explained that MTA setting results in the hydration of anhydrous mineral oxide compounds to produce calcium silicate hydrate and calcium hydroxide phases which produce expansion. This expansion is thought to enhance the seal and minimize the leakage associated with the MTA Fillapex.  Therefore, MTA Fillapex sealer due to, apart from its good flow and favorable properties, its setting expansion mechanism and above findings from this study would have a distinct advantage over AH26 sealer in promoting superior sealing with SC technique of obturation despite the latter having minimal shrinkage. ,,, However, studies employing a larger sample size with micro-computed tomography, and calculating the percentage of voids in relation to the total area of each canal section or the whole canal would assist to further validate the results of this study.
| Conclusion|| |
Within the limitations of this study, it can be concluded that the SC obturation with MTA Fillapex sealer had no voids in the apical and middle third sections and had a least overall mean area of voids. The differences were significant when compared to those with AH26 and Pulpdent sealers. SC obturation with AH26 sealer also showed the significantly lesser area of voids in the apical and middle sections and lesser overall mean area of voids when compared to those with Pulpdent sealer.
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Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4]